Inaccurate needle placement hampers the clinical outcomes of targeted prostate biopsy and focal ablations of prostate cancer despite the recent advancement in image-guidance techniques including in-bore MRI guidance and MR-TRUS fusion. In particular, the deviation of the needle from the intended insertion path due to the interaction between the needle and the surrounding tissue is a major cause of inaccurate needle placement. Our long-term goal is to develop and validate closed-loop adaptive needle insertion control to compensate for the needle deviation during needle insertion for targeted biopsy and focal treatment in the prostate. The specific contribution of this proposal is to develop and validate optical fiber-based shape-sensing needle (sensorized needle) that can detect the deviation of the needle in vivo and feed it back to the physician in real-time. Our hypothesis is that real-time feedback from the sensorized needle, using fiber Bragg gratings (FBG) optical fibers, will allow the physician to compensate for the deviation of the needle, and hence minimize the targeting errors. The technique can be combined with any type of imaging modalities, including TRUS and MRI. We will pursue the following four specific aims to test our hypothesis: (1) Develop and validate an optimized sensorized needle with embedded FBG strain sensors, (2) Develop and validate an adaptive needle guide device, and (3) validate closed-loop adaptive needle placement using the sensorized needle in vivo under MR guidance. The study will allow us to collect pilot data necessary to validate new, less invasive methods of prostate cancer treatment in a future clinical study. The proposed research is innovative because it will address the issue of needle deviation without predicting it by mechanically modeling individual patients, and potentially reduce false negatives in biopsies or suboptimal ablations in focal treatments. The new technology can be deployed in the existing clinical setup regardless of the type of guidance used (i.e. whether in-bore MR-guidance or MR-TRUS fusion guidance).